[rds-devel] Re: Looking at a proposal from the SAGE folks to have use_once memory keys.

Olaf Kirch olaf.kirch at oracle.com
Fri Jan 4 07:05:33 PST 2008


On Friday 04 January 2008 14:45, Richard Frank wrote:
> > The reason to try this is certainly valid. But I'm not sure the proposed
> > approach is the best way to do it. We rely on the peer to present the
> > key of a MR that we should destroy - what if the peer lies, or is confused?
> > The semantics of use_once buffers should be a local affair, if possible.
> >   
> The MR would be handed in with the RDMA send operation - so if the peer 
> is using the wrong MR - it was able to issue an RDMA too !

Yes, but possibly to a different MR?

> > There is a problem with RDMA and retransmits, and use_once buffers make
> > it worse. Assume
> >
> >   
> We do not retransmit RDMA operations - at least that's out intention - > 
> RDMA ops are not reliable.  I think we already do this ?

No, the code doesn't do this right now. It puts the message on the
retrans queue as is, and faithfully retransmits the whole thing.
It would be pretty easy to change, though.

Olaf
-- 
Olaf Kirch  |  --- o --- Nous sommes du soleil we love when we play
okir at lst.de |    / | \   sol.dhoop.naytheet.ah kin.ir.samse.qurax



More information about the rds-devel mailing list